Actually, Vangie, there are several ways to slow cook something.
One is on top of the stove in a cast iron pot over very low heat. I've done roasts, soups and stews this way. Or take the pot off the stove and slow cook the food in the oven.
The other way is in a slow oven with a covered roaster that has a tight-fitting lid (Boston Baked Beans were done this way for many years).
Then there the electric slow cooker. And also, a large electric roaster. Ribs can be slow cooked in the counterop roaster or regular oven.
I've slow cooked with all those methods, but it's hard to tell which one is better since they all do an equally amazing job.
They are true staples in the kitchen that will help you get the job done.
And yes, the roaster can accommodate a large crowd.